No comments on the recommended relationship among the size of the sample and the number of eigenvectors are included in [1]}. In the numerical experiments reported here, the same sample of max-min farthest faces is used to select the columns of \(W\)  to be computed by our method FSS and also for the Nyström approximation of the largest eigenvectors of \(W\) . Further, in the results obtained with the spectral method, we set the number of eigenvectors equal to the number of clusters. Moreover, as suggested in [2]}, the Nyström approximated eigenvectors of \(Q\)  are orthogonalized before applying k-means clustering.
